RMD160(3) BSD Library Functions Manual RMD160(3)NAME
RMD160Init, RMD160Update, RMD160Final, RMD160Transform, RMD160End, RMD160File, RMD160Data --
calculate the ``RIPEMD-160'' message digest
SYNOPSIS
#include <sys/types.h>
#include <rmd160.h>
void
RMD160Init(RMD160_CTX *context);
void
RMD160Update(RMD160_CTX *context, const u_char *data, u_int nbytes);
void
RMD160Final(u_char digest[20], RMD160_CTX *context);
void
RMD160Transform(uint32_t state[5], const uint32_t block[16]);
char *
RMD160End(RMD160_CTX *context, char *buf);
char *
RMD160File(char *filename, char *buf);
char *
RMD160Data(u_char *data, size_t len, char *buf);
DESCRIPTION
The RMD160 functions implement the 160-bit RIPE message digest hash algorithm (RMD-160).
RMD-160 is used to generate a condensed representation of a message called a message digest.
The algorithm takes a message less than 2^64 bits as input and produces a 160-bit digest
suitable for use as a digital signature.
The RMD160 functions are considered to be more secure than the md4(3) and md5(3) functions
and at least as secure as the sha1(3) function. All share a similar interface.
The RMD160Init() function initializes a RMD160_CTX context for use with RMD160Update(), and
RMD160Final(). The RMD160Update() function adds data of length nbytes to the RMD160_CTX
specified by context. RMD160Final() is called when all data has been added via
RMD160Update() and stores a message digest in the digest parameter. When a null pointer is
passed to RMD160Final() as first argument only the final padding will be applied and the
current context can still be used with RMD160Update().
The RMD160Transform() function is used by RMD160Update() to hash 512-bit blocks and forms
the core of the algorithm. Most programs should use the interface provided by RMD160Init(),
RMD160Update() and RMD160Final() instead of calling RMD160Transform() directly.
The RMD160End() function is a front end for RMD160Final() which converts the digest into an
ASCII representation of the 160 bit digest in hexadecimal.
The RMD160File() function calculates the digest for a file and returns the result via
RMD160End(). If RMD160File() is unable to open the file a NULL pointer is returned.
The RMD160Data() function calculates the digest of an arbitrary string and returns the
result via RMD160End().
For each of the RMD160End(), RMD160File(), and RMD160Data() functions the buf parameter
should either be a string of at least 41 characters in size or a NULL pointer. In the lat-
ter case, space will be dynamically allocated via malloc(3) and should be freed using
free(3) when it is no longer needed.
EXAMPLES
The follow code fragment will calculate the digest for the string "abc" which is
``0x8eb208f7e05d987a9b044a8e98c6b087f15a0bfc''.
RMD160_CTX rmd;
u_char results[20];
char *buf;
int n;
buf = "abc";
n = strlen(buf);
RMD160Init(&rmd);
RMD160Update(&rmd, (u_char *)buf, n);
RMD160Final(results, &rmd);
/* Print the digest as one long hex value */
printf("0x");
for (n = 0; n < 20; n++)
printf("%02x", results[n]);
putchar('\n');
Alternately, the helper functions could be used in the following way:
RMD160_CTX rmd;
u_char output[41];
char *buf = "abc";
printf("0x%s\n", RMD160Data(buf, strlen(buf), output));
SEE ALSOrmd160(1), md4(3), md5(3), sha1(3)
H. Dobbertin, A. Bosselaers, B. Preneel, RIPEMD-160, a strengthened version of RIPEMD.
Information technology - Security techniques - Hash-functions - Part 3: Dedicated hash-
functions, ISO/IEC 10118-3.
H. Dobbertin, A. Bosselaers, B. Preneel, "The RIPEMD-160 cryptographic hash function", Dr.
Dobb's Journal, Vol. 22, No. 1, pp. 24-28, January 1997.
HISTORY
The RMD-160 functions appeared in OpenBSD 2.1.
AUTHORS
This implementation of RMD-160 was written by Antoon Bosselaers.
The RMD160End(), RMD160File(), and RMD160Data() helper functions are derived from code writ-
ten by Poul-Henning Kamp.
BUGS
If a message digest is to be copied to a multi-byte type (ie: an array of five 32-bit inte-
gers) it will be necessary to perform byte swapping on little endian machines such as the
i386, alpha, and VAX.
BSD July 16, 1997 BSD